Phentermine vs. Adderall: Differences, similarities, and which one is better for ADHD

In this article:

• Drug overview & main differences
• Conditions treated
• Efficacy
• Insurance coverage & cost comparison
• Possible side effects
• Drug interactions
• Warnings
• FAQ

In this article

• Drug overview & main differences
• Conditions treated
• Efficacy
• Insurance coverage & cost comparison
• Possible side effects
• Drug interactions
• Warnings
• FAQ

Phentermine and Adderall are prescription drugs that stimulate the central nervous system (CNS), which encompasses the brain and spinal cord. Specifically, they work by increasing the release of certain chemicals or neurotransmitters called dopamine and norepinephrine in the brain, which may help to suppress appetite and improve focus or attention.

Although both drugs are CNS stimulants taken as daily pills, they are approved by the U.S. Food and Drug Administration (FDA) for different uses. However, some individuals may use these medications for similar reasons, even if these uses are off-label or lack FDA approval. In addition, each medication comes with its side effects, costs, and insurance coverage, which patients should discuss with their healthcare provider.

Read on to learn more about the similarities and differences between phentermine and Adderall. 

RELATED: What is phentermine? | What is Adderall?

What are the main differences between phentermine and Adderall?

Phentermine is a generic drug known under the brand names Adipex, Lomaira, Fastin, and others. It is also combined with topiramate for weight loss under the brand name Qsymia. Phentermine is a CNS stimulant but, more specifically, falls under a drug class known as anorectics or sympathomimetic amines, closely related to amphetamines. It is typically taken as a 37.5 mg oral tablet once daily, with the usual course of treatment spanning a few weeks to a few months.

Adderall is a brand-name drug that contains a combination of amphetamine and dextroamphetamine. Adderall is an immediate-release (IR) oral tablet, typically taken multiple times throughout the day, and an extended-release (XR) form once daily. Typical dosing for regular Adderall ranges from 5 mg to 30 mg per day, split over multiple doses, with each dose lasting around four to six hours. It is generally used long-term to help manage symptoms of attention deficit hyperactivity disorder (ADHD).

Conditions treated by phentermine and Adderall

Phentermine is FDA-approved for weight loss. It can be used to manage weight in people with obesity (BMI of 30 kg/m2 or higher) or people who are overweight (BMI of 27 kg/m2 or higher) with weight-related conditions like high blood pressure or diabetes. It acts as an appetite suppressant and is meant to be used alongside lifestyle changes, such as a reduced-calorie diet and increased physical activity.

Adderall is FDA-approved to treat ADHD, a neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity. In addition, it’s approved to treat narcolepsy, a chronic sleep disorder that causes overwhelming daytime drowsiness and sudden attacks of sleep.

Because both medications act as stimulants, they may be used off-label for similar purposes. Although Adderall is not approved for weight loss, studies show that Adderall can cause weight loss as a side effect. In addition, case reports have found that phentermine may potentially help people with ADHD. Healthcare providers may prescribe medications off-label for purposes not approved by the FDA based on research and clinical judgment. 

Is phentermine or Adderall more effective?

Phentermine and Adderall are both effective medications. The better option will generally depend on the intended use and other factors. There are limited head-to-head studies and clinical trials comparing phentermine and Adderall. 

Phentermine may be a preferred option as an appetite suppressant due to its FDA approval for weight loss. However, the use of Adderall for weight loss may be relatively common, with decreased appetite and weight loss being a common side effect.

The standard use of Adderall is for ADHD and narcolepsy. However, phentermine may also be used for ADHD and narcolepsy, with studies suggesting its effectiveness for both conditions. 

It’s recommended to consult a healthcare provider when determining the most appropriate treatment option. 

Coverage and cost comparison of phentermine vs. Adderall

Adderall is commonly covered by many insurance plans, with the cost depending on the plan’s specifics. Generic versions tend to be less expensive. In contrast, phentermine coverage by insurance plans is more inconsistent due to its use for weight loss. While Adderall is often covered under Medicare Part D, the coverage for phentermine may be more limited, as weight loss medications are not always included.

For those without insurance, the retail costs of phentermine and Adderall can vary. As a generic medication, phentermine may be cheaper than brand-name Adderall. However, patients can save on the retail price of these medications by using a SingleCare card. SingleCare offers discounts on both phentermine and Adderall, which may lower the cost significantly, especially for those without insurance.

Common side effects of phentermine vs. Adderall

Phentermine and Adderall share similar side effects as stimulant medications. Common side effects of both medicines may include insomnia or trouble sleeping, dry mouth, decreased appetite, nausea, tremor, diarrhea, and constipation. 

Both medications can lead to more serious side effects. For example, both medicines may increase heart rate and cause high blood pressure (hypertension), leading to potential heart problems. Allergic reactions are rare but possible while taking these medications, often requiring immediate medical attention. 

Discuss all potential side effects with a healthcare provider before starting treatment. 

This may not be a complete list of adverse effects that can occur. Please refer to your doctor or healthcare provider to learn more. Source: DailyMed (Phentermine), DailyMed (Adderall) 

Drug interactions of phentermine vs. Adderall

Phentermine and Adderall share similar drug interactions. They should not be used with medications known as monoamine oxidase inhibitors (MAOIs) or within 14 days of stopping an MAOI. Combining these medications with MAOIs may increase the risk of dangerously high blood pressure and serotonin syndrome.

Phentermine and Adderall may need to be used with caution while taking serotonergic drugs, especially certain antidepressants. Taking phentermine or Adderall with selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), or tricyclic antidepressants (TCAs) may increase the risk of serotonin syndrome. 

Phentermine and Adderall may reduce the blood pressure-lowering effects of blood pressure medications. Regular blood pressure monitoring is often recommended when taking these medications together.

As you lose weight with phentermine, your insulin or diabetic medication dosage may need to be adjusted. Your healthcare provider may need to monitor blood sugar levels and make changes to your diabetic plan during and after phentermine treatment. 

Adderall may not be absorbed as quickly when taken with proton pump inhibitors (PPIs) because they reduce stomach acid. Acidifying agents might decrease how much Adderall the body absorbs, leading to reduced effectiveness. Alkalinizing agents may increase the blood levels of Adderall, leading to increased effects.

Tell a healthcare provider about any medications, including over-the-counter medications and herbal supplements, before starting treatment with phentermine or Adderall. 

This is not a complete list of drug interactions. Please consult your doctor before taking these medications.

RELATED: Phentermine alternatives | Adderall alternatives

Warnings of phentermine and Adderall

Phentermine and Adderall may have similar warnings and precautions. 

Phentermine should not be combined with other weight loss products or serotonergic agents. Monitor for symptoms of high blood pressure in the lungs (pulmonary hypertension) and discontinue treatment if concerning signs, such as shortness of breath, chest pain, and dizziness, arise. Further caution is advised as phentermine may impair the ability to perform tasks like driving or operating machinery.

Regarding the use of Adderall, people with serious heart disease may need to use caution, as sudden death has been reported in some cases. In addition, Adderall can lead to worsened psychiatric conditions, delayed growth in children, and seizures in certain individuals, among other problems.

Adderall is a Schedule II controlled substance that has a high potential for abuse and misuse, which may lead to substance use disorder and addiction. Phentermine, on the other hand, is classified as a Schedule IV controlled substance with a lower potential for abuse and dependence than Adderall.

Phentermine should not be used during pregnancy or breastfeeding, as it may harm the fetus or the baby. Adderall should also be avoided during pregnancy and breastfeeding unless necessary because it can pass into breast milk, potentially causing harm to a nursing infant. 

Frequently asked questions about phentermine vs. Adderall

What is phentermine?

Phentermine is a prescription medication that is FDA-approved for weight loss. It acts as an appetite suppressant and is available in different dosage forms, such as oral tablets and capsules. It is typically taken once daily.

What is Adderall?

Adderall contains amphetamine salts and is primarily used to treat ADHD symptoms. It also helps in the management of narcolepsy. Adderall is available as an oral tablet that’s taken every four to six hours. An extended-release tablet that’s taken once daily is also available.

Are phentermine and Adderall the same?

No, phentermine and Adderall are not the same. Although both act as stimulant drugs, phentermine is FDA-approved for weight management, while Adderall, which is a combination of amphetamine and dextroamphetamine, is approved for ADHD and narcolepsy.

Is phentermine or Adderall better?

The effectiveness of phentermine and Adderall depends on the person’s prescribed condition and response to treatment. Phentermine may be a better choice for weight loss, although Adderall is sometimes used off-label for this purpose. Although Adderall is approved for ADHD, phentermine may sometimes be used off-label to manage ADHD. Consult a healthcare provider for the most effective option. 

Can I use phentermine or Adderall while pregnant?

Phentermine and Adderall both carry risks during pregnancy and can only be used if the potential benefits justify the possible risks to the unborn baby.

Can I use phentermine or Adderall with alcohol?

Avoid consuming alcohol with either phentermine or Adderall, as it may increase the risk of side effects with phentermine and Adderall, such as dizziness and headache. Drinking alcohol may also increase the risk of potential substance abuse with Adderall and phentermine.